Dum Ka Biryani, Make for each other

Version 1.0 February 2011 GNU Free Documentation License Shakthi Kannan [email protected] http://www.shakthimaan.com

() Dum Ka Biryani, Make for each other 1 / 1 Dum Ka Biryani

() Dum Ka Biryani, Make for each other 2 / 1 2.1 What a Rule Looks Like

Makefile target : prerequisites ... recipe ......

Tab before recipe!

() Dum Ka Biryani, Make for each other 3 / 1 2.2 A Simple Makefile

Makefile biryani : masala.o rice.o onion.o curd.o coriander.o meat.o cc -o biryani masala.o rice.o onion.o curd.o coriander.o meat.o

masala.o : masala.c masala.h defs.h cc -c masala.c

rice.o : rice.c rice.h defs.h cc -c rice.c

onion.o : onion.c defs.h cc -c onion.c

curd.o : curd.c defs.h cc -c curd.c

coriander.o : coriander.c defs.h cc -c coriander.c

meat.o : meat.c defs.h cc -c meat.c

clean: rm biryani \ masala.o rice.o onion.o curd.o coriander.o meat.o

() Dum Ka Biryani, Make for each other 4 / 1 2.4 Variables Make Makefiles Simpler

Makefile objects = masala.o rice.o onion.o curd.o coriander.o meat.o

biryani : $(objects) cc -o biryani $(objects)

masala.o : masala.c masala.h defs.h cc -c masala.c

rice.o : rice.c rice.h defs.h cc -c rice.c

onion.o : onion.c defs.h cc -c onion.c

curd.o : curd.c defs.h cc -c curd.c

coriander.o : coriander.c defs.h cc -c coriander.c

meat.o : meat.c defs.h cc -c meat.c

clean: rm biryani $(objects)

() Dum Ka Biryani, Make for each other 5 / 1 2.5 Letting make Deduce the Recipes

Makefile objects = masala.o rice.o onion.o curd.o coriander.o meat.o

biryani : $(objects) cc -o biryani $(objects)

masala.o : masala.h defs.h

rice.o : rice.h defs.h

onion.o : defs.h

curd.o : defs.h

coriander.o : defs.h

meat.o : defs.h

clean: rm biryani $(objects)

() Dum Ka Biryani, Make for each other 6 / 1 2.6 Another Style of Makefile

Makefile objects = masala.o rice.o onion.o curd.o coriander.o meat.o

biryani : $(objects) cc -o biryani $(objects)

$(objects) : defs.h

masala.o : masala.h

rice.o : rice.h

clean: rm biryani $(objects)

() Dum Ka Biryani, Make for each other 7 / 1 2.7 Rules for Cleaning the Directory

Makefile objects = masala.o rice.o onion.o curd.o coriander.o meat.o

biryani : $(objects) cc -o biryani $(objects)

$(objects) : defs.h

masala.o : masala.h

rice.o : rice.h

.PHONY : clean clean: -rm biryani $(objects)

() Dum Ka Biryani, Make for each other 8 / 1 3.1 What Makefiles Contain

* Explicit rule onion.o : onion.c defs.h cc -c onion.c

* Implicit rule masala.o : masala.h

* Variable definition objects = masala.o rice.o onion.o curd.o coriander.o meat.o

* Directive ifeq ($(CC), gcc) libs=$(libs for gcc) else libs=$(normal libs) endif

* Comments # This is a comment

() Dum Ka Biryani, Make for each other 9 / 1 $ make $ make -f myMakefile $ make --file=myMakefile

3.2 What Name to Give Your Makefile

Default * GNUMakefile * makefile * Makefile

() Dum Ka Biryani, Make for each other 10 / 1 3.2 What Name to Give Your Makefile

Default * GNUMakefile * makefile * Makefile

$ make $ make -f myMakefile $ make --file=myMakefile

() Dum Ka Biryani, Make for each other 10 / 1 $ make $ make -I $ make --include-dir

3.3 Including Other Makefiles

* Syntax include filenames... * Regex and variables allowed include foo *.mk $(bar) * To ignore Makefile if not found -include filenames...

() Dum Ka Biryani, Make for each other 11 / 1 3.3 Including Other Makefiles

* Syntax include filenames... * Regex and variables allowed include foo *.mk $(bar) * To ignore Makefile if not found -include filenames...

$ make $ make -I $ make --include-dir

() Dum Ka Biryani, Make for each other 11 / 1 $ make $ make meat

3.6 Overriding Part of Another Makefile

GNUmakefile meat: cc -c vegetables.c

%: force @$(MAKE) -f Makefile $@ force: ;

() Dum Ka Biryani, Make for each other 12 / 1 3.6 Overriding Part of Another Makefile

GNUmakefile meat: cc -c vegetables.c

%: force @$(MAKE) -f Makefile $@ force: ;

$ make $ make meat

() Dum Ka Biryani, Make for each other 12 / 1 3.7 How make Reads a Makefile

First phase * Reads all makefiles * Reads included makefiles * Internalize variables, values, implicit and explicit rules * Constructs dependency graph of targets and pre-requisites * immediate: expansion in phase one Second phase * Determines which targets need to be re-built * Invokes the necessary rules * deferred: expansion in phase two

() Dum Ka Biryani, Make for each other 13 / 1 3.7 How make Reads a Makefile

Variable assignment * immediate = deferred * immediate ?= deferred * immediate := immediate * immediate += deferred or immediate immediate, if variable was previously set as a simple variable (:=) deferred, otherwise Second phase * Determines which targets need to be re-built * Invokes the necessary rules * deferred: expansion in phase two

() Dum Ka Biryani, Make for each other 14 / 1 3.7 How make Reads a Makefile

Conditional Directives * immediate Rule Definition Makefile target : prerequisites ... recipe ......

Makefile immediate : immediate ; deferred deferred

() Dum Ka Biryani, Make for each other 15 / 1 4.2 Rule Syntax

* First target as default, if not specified. * A rule tells make two things: when the targets are out of date (prerequisites), and how to update them (recipe) when necessary.

Makefile target : prerequisites ... recipe ......

Makefile target : prerequisites ; recipe recipe ......

() Dum Ka Biryani, Make for each other 16 / 1 4.4 Using Wildcard Characters in File Names

Makefile clean : rm -f *.o

Wildcard expansion does not happen in variable definition

Makefile objects = *.o

Use Wildcard function! Makefile objects = $(wildcard *.o)

() Dum Ka Biryani, Make for each other 17 / 1 4.5 Searching Directories for Prerequisites

VPATH make variable VPATH = src:../headers vpath Directive

Makefile vpath pattern directories vpath %.h ../headers

To clear search paths:

Makefile vpath pattern vpath %.h

vpath

() Dum Ka Biryani, Make for each other 18 / 1 4.5.4 Writing Recipes with Directory Search

Automatic variables $ˆ all prerequisites $@ target $< first prerequisite

Makefile coriander.o : coriander.c cc -c $(CFLAGS) $^ -o $@

Makefile masala.o : masala.c masala.h defs.h cc -c $(CFLAGS) $< -o $@

() Dum Ka Biryani, Make for each other 19 / 1 4.6 Phony Targets Error in submake ignored: Makefile SUBDIRS = masala rice onion

subdirs : for dir in $(SUBDIRS); do \ $(MAKE) -C $$dir; \ done

Makefile SUBDIRS = masala rice onion

.PHONY : subdirs $(SUBDIRS) subdirs: $(SUBDIRS)

$(SUBDIRS): $(MAKE) -C $@

() Dum Ka Biryani, Make for each other 20 / 1 4.12 Static Pattern Rules

* Override implicit rule. * No uncertainity.

Makefile targets ... : target-pattern: prereq-patterns ... recipe ...

Makefile objects = curd.o coriander.o masala.o

all: $(objects)

$(objects): %.o: %.c $(CC) -c $(CFLAGS) $< -o $@

() Dum Ka Biryani, Make for each other 21 / 1 $ make In a cooking vessel add a layer of semi-cooked Basmati rice Add meat on this rice layer Add another layer of rice Sprinkle the ingredients with water and cook

5.1 Recipe Syntax

* Follows shell syntax. * Backslash-newline pairs are preserved and passed to the shell.

Makefile all : @echo In a cooking vessel\ add a layer of semi-cooked Basmati rice @echo Add meat on this\ rice layer @echo Add another layer \ of rice @echo Sprinkle the ingredients with water and cook

() Dum Ka Biryani, Make for each other 22 / 1 5.1 Recipe Syntax

* Follows shell syntax. * Backslash-newline pairs are preserved and passed to the shell.

Makefile all : @echo In a cooking vessel\ add a layer of semi-cooked Basmati rice @echo Add meat on this\ rice layer @echo Add another layer \ of rice @echo Sprinkle the ingredients with water and cook

$ make In a cooking vessel add a layer of semi-cooked Basmati rice Add meat on this rice layer Add another layer of rice Sprinkle the ingredients with water and cook

() Dum Ka Biryani, Make for each other 22 / 1 $ make masala rice onion

5.1.2 Using Variables in Recipes

Makefile LIST = masala rice onion

all: for i in $(LIST); do \ echo $$i; \ done

() Dum Ka Biryani, Make for each other 23 / 1 5.1.2 Using Variables in Recipes

Makefile LIST = masala rice onion

all: for i in $(LIST); do \ echo $$i; \ done

$ make masala rice onion

() Dum Ka Biryani, Make for each other 23 / 1 $ make $ make -j $ make --jobs

$ make -l $ make --max-load

5.4 Parallel Execution

* -j number, number of recipies to execute in parallel. * -l number, number (limit) of jobs to run in parallel.

() Dum Ka Biryani, Make for each other 24 / 1 5.4 Parallel Execution

* -j number, number of recipies to execute in parallel. * -l number, number (limit) of jobs to run in parallel.

$ make $ make -j $ make --jobs

$ make -l $ make --max-load

() Dum Ka Biryani, Make for each other 24 / 1 5.5 Errors in Recipes

* Ignore errors in a recipe line.

Makefile clean : -rm -f *.o

() Dum Ka Biryani, Make for each other 25 / 1 5.7 Recursive Use of make

* Recursive make commands should always use the variable MAKE.

Makefile subsystem : cd subdir && $(MAKE)

Makefile subsystem : $(MAKE) -C subdir

() Dum Ka Biryani, Make for each other 26 / 1 5.7.2 Communicating Variables to Sub-make

Makefile variable = value

export variable ...

unexport variable ...

Makefile export variable = value

export variable := value

export variable += value

() Dum Ka Biryani, Make for each other 27 / 1 $ make $ make mix Adding green chillies Adding ginger garlic paste Adding cinnamon, cardamom Adding fried onions Adding coriander and mint leaves

5.8 Defining Canned Recipes

Makefile define mix-masala= @echo "Adding green chillies" @echo "Adding ginger garlic paste" @echo "Adding cinnamon, cardamom" @echo "Adding fried onions" @echo "Adding coriander and mint leaves" endef

mix: $(mix-masala)

() Dum Ka Biryani, Make for each other 28 / 1 5.8 Defining Canned Recipes

Makefile define mix-masala= @echo "Adding green chillies" @echo "Adding ginger garlic paste" @echo "Adding cinnamon, cardamom" @echo "Adding fried onions" @echo "Adding coriander and mint leaves" endef

mix: $(mix-masala)

$ make $ make mix Adding green chillies Adding ginger garlic paste Adding cinnamon, cardamom Adding fried onions Adding coriander and mint leaves

() Dum Ka Biryani, Make for each other 28 / 1 $ make green chillies and red chillie powder

6.2 The Two Flavors of Variables

* Recursively Expanded variable

Makefile spice = $(chillies) chillies = $(both) both = green chillies and red chillie powder

all: ; echo $(spice)

() Dum Ka Biryani, Make for each other 29 / 1 6.2 The Two Flavors of Variables

* Recursively Expanded variable

Makefile spice = $(chillies) chillies = $(both) both = green chillies and red chillie powder

all: ; echo $(spice)

$ make green chillies and red chillie powder

() Dum Ka Biryani, Make for each other 29 / 1 $ make red chillie powder, green chillies green chillies

6.2 The Two Flavors of Variables

* Simply Expanded variable

Makefile chillie := red chillie spice := $(chillie) powder, green chillies chillie := green chillies

all: echo $(spice) echo $(chillie)

() Dum Ka Biryani, Make for each other 30 / 1 6.2 The Two Flavors of Variables

* Simply Expanded variable

Makefile chillie := red chillie spice := $(chillie) powder, green chillies chillie := green chillies

all: echo $(spice) echo $(chillie)

$ make red chillie powder, green chillies green chillies

() Dum Ka Biryani, Make for each other 30 / 1 6.2 The Two Flavors of Variables

* Conditional Variable assignment operator

Makefile ifeq ($(origin RICE), undefined) RICE = Basmati rice endif

Makefile RICE ?= Basmati rice

() Dum Ka Biryani, Make for each other 31 / 1 6.3.1 Substitution References

Makefile masala := chillies.o onions.o garlic.o ginger.o biryani := $(masala:.o=.c)

Makefile masala := chillies.o onions.o garlic.o ginger.o biryani := $(masala:%.o=%.c)

* ’biryani’ is set to ’chillies.c onions.c garlic.c ginger.c’

() Dum Ka Biryani, Make for each other 32 / 1 $ make green coriander leaves

6.3.2 Computed Variable Names

Makefile greeny = coriander coriander = green coriander leaves leaves := $($(greeny))

all: @echo $(leaves)

() Dum Ka Biryani, Make for each other 33 / 1 6.3.2 Computed Variable Names

Makefile greeny = coriander coriander = green coriander leaves leaves := $($(greeny))

all: @echo $(leaves)

$ make green coriander leaves

() Dum Ka Biryani, Make for each other 33 / 1 6.6 Appending More Text to Variables

Makefile objects = masala.o rice.o onion.o curd.o ... objects += coriander.o

Makefile CFLAGS = $(includes) -O ... CFLAGS += -pg

() Dum Ka Biryani, Make for each other 34 / 1 6.7 The override Directive

Makefile override variable = value

override variable := value

override variable += more text

Makefile override CFLAGS += -g

override define masala= more-masala endef

() Dum Ka Biryani, Make for each other 35 / 1 6.9 Undefining Variables

Makefile water := saffron water leaves = mint leaves

undefine water undefine leaves

Makefile override undefine CFLAGS

() Dum Ka Biryani, Make for each other 36 / 1 6.11 Target-specific Variable Values

Makefile target ... : variable-assignment

Makefile prog : CFLAGS = -g prog : masala.o rice.o onion.o

() Dum Ka Biryani, Make for each other 37 / 1 6.12 Pattern-specific Variable Values

Makefile pattern ... : variable-assignment

Makefile %.o : CFLAGS = -O

Makefile %.o: %.c $(CC) -c $(CFLAGS) $(CPPFLAGS) $< -o $@

lib/%.o: CFLAGS := -fPIC -g %.o: CFLAGS := -g

all: rice.o lib/masala.o

() Dum Ka Biryani, Make for each other 38 / 1 7.1 Example of a Conditional

Makefile libs for gcc = -lgnu

normal libs =

biryani : $(objects) ifeq ($(CC), gcc) libs=$(libs for gcc) else libs=$(normal libs) endif

() Dum Ka Biryani, Make for each other 39 / 1 7.2 Syntax of Conditionals

Makefile conditional-directive text-if-true endif

Makefile conditional-directive text-if-true else text-if-false endif

Makefile conditional-directive text-if-one-is-true endif else conditional-directive text-if-true else text-if-false endif

() Dum Ka Biryani, Make for each other 40 / 1 7.2 Syntax of Conditionals

Four conditional directives: * ifeq ifeq ($(CC), gcc) * ifneq ifneq ($(STRIP), strip) * ifdef ifdef $(LIBS) * ifndef ifndef $(CFLAGS)

() Dum Ka Biryani, Make for each other 41 / 1 8.1 Function Call Syntax

Makefile $(function arguments)

${function arguments}

Makefile comma := , empty := space:= $(empty) $(empty)

masala:= chillies onion garlic ginger list:= $(subst $(space),$(comma),$(masala))

’list’ is now ’chillies,onion,garlic,ginger’

() Dum Ka Biryani, Make for each other 42 / 1 8.2 Functions for String Substitution and Analysis

Makefile $(subst from,to,text )

$(patsubst pattern,replacement,text )

$(strip string )

$(findstring find,in )

$(filter pattern...,text )

$(filter-out pattern...,text )

$(sort list )

$(word n, text )

() Dum Ka Biryani, Make for each other 43 / 1 8.3 Functions for File Names

Makefile $(dir names... )

$(notdir names... )

$(suffix names... )

$(basename names... )

$(addsuffix suffix,names... )

$(addprefix prefix,names... )

$(join list1, list2 )

$(wildcard pattern )

() Dum Ka Biryani, Make for each other 44 / 1 8.4 Functions for Conditionals

Makefile $(if condition,then-part[,else-part] )

$(or condition1[,condition2[,condition3...]] )

$(and condition1[,condition2[,condition3...]] )

() Dum Ka Biryani, Make for each other 45 / 1 8.5 The foreach Function

Makefile $(foreach var,list,text )

Makefile find files = $(wildcard $(dir)/*)

dirs := masala rice leaves

files := $(foreach dir, $(dirs), $(find files))

() Dum Ka Biryani, Make for each other 46 / 1 8.6 The call Function

Makefile $(call variable,param,param,... )

Makefile reverse = $(2) $(1)

make = $(call reverse,cook,mix)

’make’ contains ’mix cook’

() Dum Ka Biryani, Make for each other 47 / 1 $ make ATH /usr/local/bin:/usr/bin:/bin:/usr/local/sbin:/usr/sbin:/sbin

8.7 The value Function

Makefile $(value variable )

Makefile LIST = $PATH

all: @echo $(LIST) @echo $(value LIST)

() Dum Ka Biryani, Make for each other 48 / 1 8.7 The value Function

Makefile $(value variable )

Makefile LIST = $PATH

all: @echo $(LIST) @echo $(value LIST)

$ make ATH /usr/local/bin:/usr/bin:/bin:/usr/local/sbin:/usr/sbin:/sbin

() Dum Ka Biryani, Make for each other 48 / 1 8.9 The origin Function

Makefile $(origin variable )

How the variable was defined: * undefined * default * environment * environment override * file * command line * automatic

() Dum Ka Biryani, Make for each other 49 / 1 8.10 The flavor Function

Makefile $(flavor variable )

Flavor of the variable: * undefined * recursively expanded variable * simply expanded variable

() Dum Ka Biryani, Make for each other 50 / 1 8.11 The shell Function

Makefile contents := $(shell cat onion.c)

Makefile files := $(shell echo *.c)

() Dum Ka Biryani, Make for each other 51 / 1 References

GNU Make: http://www.gnu.org/software/make/

GNU Make Manual: http://www.gnu.org/software/make/manual/

Dum Ka Biryani, Make for each other (sources): http://www.shakthimaan.com/downloads.html#dum-ka-biryani-make-for-each-other

Symbols in LaTeX and HTML: http://newton.ex.ac.uk/research/qsystems/people/sque/symbols/

() Dum Ka Biryani, Make for each other 52 / 1